Carburetor



April 8, 1941.

L. BECK CARBURETOR Filed July 10, 1937 Patented Apr. 8, 1941 CARBURETORLudwig Beck, Berlin, Germany, assignor of onethird to Ludwig Bertele,Berlin-Steglitz, Germany, and one-third to Alwin Dustcrloh, Sprockhovel,Germany Application July 10, 1937, Serial No. 152,885 In Germany July13, 1936 4 Claims.

This invention relates to carburetors for internal combustion enginesserving for driving vehicles; and it relates especially to suchcarburetors in which the air is admixed to the fuel prior to injectingthe same into the mixing chamber, and in which the amount of the airsupplied for that purpose into the fuel channel is controlled in apositive manner.

In the present improved carburetor the amount of the air admixed to thefuel prior to injecting it into the mixing chamber is subjected to apositive control which constitutes a continual function of the fall ofpressure" at the throttling member of the carburetor.

A special feature of the invention consists in a pneumatic controldevice for the actuation of the valve through which the air isintroduced into the fuel.

Another special feature of the invention is a carburetor, the airchannels and fuel channels of which communicate with the suction pipeat' selective places, with the aid" of which a continual dependency ofthe amounts of air introduced into the fuel can be obtained at thethrottling member of the carburetor without the co-action of a valve.

Finally, the invention comprises a plurality of auxiliary means by whichcertain carburetor properties particularly important for vehicle motorsequipped with carburetors of the above mentioned type are furtherimproved.

The invention is illustrated diagrammatically and by way of example inthe accompanying drawing, in which Figure 1 shows a diagram representingthe fall of pressure at the carburetor throttling member, as well as theactual and theoretically correct rates of fuel supply. Figure 2 is anaxial section through a carburetor provided with a diaphragm valvecontrolling the amount of air introduced into the fuel. Figure 3 ispartly a side-view of, and partly an axial section through, a carburetorin which the amount of air introduced into the fuel is controlled purelyaerodynamically. Figure 4 is chiefly an axial section through acarburetor in which the amount of air introduced into the fuel issubjected: to an additional control by means of an air-valve positivelycoupled with the throttling member of the carburetor; and Figure 5 is asimilar illustration showing a modification of the constructional formillustrated in Fig. 4, all as fully described hereinafter.

Referring to Fig. 1, the dot-and' dash line A represents the fall ofpressure arising in the carburetor of a vehicle motor at the throttlevalve when running with normal load (running with slowly increasingspeed on a level road) said valve being quite gradually opened from 0 toThe dash-line curve B indicates the fuel amount with which the motor issupplied: per second by a normal carburetor, and the full-line curve Cshows by way of comparison the amount of fuel with which the motorshould be supplied per second if the proportion of the fuel and the airmost favorable for all positions of the throttling member is to beattained and maintained and the greatest performance is to be obtainedwith the smallest consumption of fuel.

It appears from the diagram that there are considerable deviationsbetween the curves B and C. To produce an ideal carburetor it would benecessary to correct the fuel supply in such a manner that the curve Bpasses over into the curve C. Now, I have discovered that the course ofthe curve A corresponds nearly accurately with the reciprocal value ofthe correction function required to transform the curve B into the curveC. There is, therefore, for all abscissa values of Fig. 1 approximatelytrue the equation in which 70 denotes a definite'conversion coefficient.The invention utilises this discovery in that the fall of pressure A isemployed for controlling the amount of air which is usually admixed tothe fuel to be introduced into the carburetor prior to the fuel beinginjected into the mixing chamber.

In Fig. 2 is shown a carburetor in which the amount of air is regulatedwith the aid of a pneu matically controlled valve. of the carburetorcontains in the usual manner a throttle valve 2, as well as a venturi 3into which extends the nozzle 4. The dash-and-dot line (1-1) indicatesthe level of the fuel. The fuel arriving from the float receptacle (notshown) enters.

through the pipe 5 and flows through the (exchangeable) restrictedpassage 6 into the nozzle 4. The nozzle is surrounded by a tubularstorage space I which communicates with the open air through a valveformed by a slit piston 9 shiftable in a correspondingly slit cylinderIi].

The piston 9 is controlled. by a diaphragm II which separates chambersI2 and I3 air-tight from one another and consists preferably of anundu'lated sheet-metal disk such as is generally used in aneroidbarometers. The chamber I2 is connected by a passage I4 with thatportion of the intake tube I which is located behind the throttle Theintake pipe I valve 2, and the chamber I3 is connected by a passage ISwith that portion of the intake tube which is located between thethrottle valve and the venturi' 3. The diaphragm constitutes, therefore,a sort of manometer which measures the fall of pressure at the valve 2and transmits to the valve piston 9 such movements as correspond withthe course of the curve A (Fig. 1).

The valve 9-H) is so adjusted that it opens the air supply passage themore, the more the diaphragm is bent to the left, that is to say, thehigher the fall of pressure rises at the throttle valve 2. Owingthereto, there is admixed to the fuel through the air passage 8, infront of the nozzle 4, an amount of air which is the larger, the greaterthe fall of pressure at the throttle flap becomes. Of decisiveimportance in this respect is the fact that the channel l5 does notextend to the open air, but terminates behind the venturi 3 in theintake tube I, as in this way there is automatically attained anincrease of the fuel supply when the motor runs with a greater load.

If it be assumed, for example, that the car is running with a speed of60 kilometers per hour on a level road, the throttle valve will be openabout 45. When the car reaches a gradient in the road, the throttlevalve must be opened for about 55 to 60 so that in spite of theincreased load the same speed as before can be maintained. Even if inthis case the suction acting on the nozzle 4 does not vary, and when anormal carburetor would not deliver an excess of fuel for overcoming theincreased load, the improved carburetor forming the subject-matter ofthe present invention will automatically increase the amount of fuelsupplied. When the car passes from the level portion of the road to agradient, and the throttle valve is opened for 60, there will obviouslyarise at the valve an essentially smaller fall of pressure than if itwere opened only for 45 at the same suction speed, in consequencewhereof the piston 9 will be moved to the right and will decrease theamount of air arriving at the nozzle 4 through the channel 8. A largeramount of fuel will, therefore, be sucked into the carburetor when theload on the motor increases.

In Fig. 3 there is shown a carburetor in which the effect aimed at isattained in a still simpler way. The air streams through the suctionpipe Q6 of this carburetor in a downward direction. The injection nozzleH extends into said pipe [6 at a point below the throttle valve. Thenozzle communicates with a fore-space terminate the fuel pipe 20 and thetwo air channels 2| and 22. The channel 22 communicates directly withthe atmosphere on the one hand by means of the branch channel 23, thesectional area of which can be subjected to a fine-adjustment by thevalve-screw 24, and on the other hand by means of the branch-channel 25,the orifice of which can be adjusted in somewhat large steps by therotary valve 26. The air channel 22 terminates in the suction pipe l6between the throttle Valve l8 and the venturi 21.

From Fig. 3 it appears at once that the amount of air streaming into thefore-space l9 through the channel 2i must depend upon the difference ofpressure between the portions x and y of the suction tube, that is tosay, on the fall of pressure at the throttle valve it. This carburetortherefore, presents all the advantages claimed for the carburetor shownin Fig. 2, but besides those advantages it presents the furtheradvantage [9 in which that its construction is materially simpler andthat it can be operated Without the employment of a benzene pump and afloat device, since by a suitable adjustment of the air valves 24 and 2Ga pressure below the atmospheric pressure can be produced in thefore-space l9 which fully sufiices to suck the fuel up to the nozzle Hfrom a receptacle situated comparatively considerably therebelow. Forthe rest, a temporary additional acceleration, or a change of thecarburetor from summer service to winter service can be had in aparticularly simple manner with the aid of the rotary valve 25 which canbe actuated, counter to the action of a helical tension spring, by meansof a wire cable 29 operable from the control board (not shown) of thecar.

The further modification illustrated in Fig. 4 shows a carburetor whichresembles in many respects the carburetor shown in Fig. 3 and in whichthe members corresponding with equivalent members of Fig. 3 bear thesame reference numerals. Said modification is equipped with an auxiliarydevice by means of which the fuel supply is rendered positivelydependent upon the position of the throttle valve at the time being. Theauxiliary device consists of a slide-valve 39 inserted into the airchannel 2! and moved through the intermediary of a rod 3|, by means of acam 32 secured to the shaft of the throttle valve 8. The more this flapis opened, the more is the valve closed. The most important advantagewhich this modification presents is that the channel 2| may be madelarge enough to prevent completely any supply of fuel to the nozzle I!if the throttle valve is temporarily closed during running at fullspeed. Furthermore, said auxiliary device renders it possible to startwith an increased speed.

In Fig. 5 is shown a carburetor in which the same success is attained inanother manner. The air sucked into the carbur tor streams in an upwarddirection through the suction pipe 33. The nozzle 34 is, therefore,again arranged behind the throttle valve 35 (indicated only by dottedlines). The parts 23 and 24 correspond to the same numbered parts inFig. 3 and provide for admitting a regulated amount of air to theforechamber 36, as determined by the adjustment of 24. The air channel3'l, terminating at one end at the fore-chamber 36, terminates at theother end at the suction tube 33 in front of the throttle-valve 35,similar to channel 2| in Fig. 3, but there is provided a branch 38(shown in dotted lines) which leads to an aperture 39 opening to theatmosphere. The cam 43 which is affixed to the shaft of the throttlevalve 35 can close said aperture more or less, according to itsposition. The branch 33 modifies the effect of channel 31 and causes anadditional amount of air to be supplied to chamber 36 at low throttleopenings and when the throttle is closed.

When the valve 35 is completely closed a lug 41 on the cam lifts a rod42 which is suspended from a double-armed lever 43, the other and longerarm of which bears upon the upper end of a valve rod 44, at the otherend of which is a ball-valve 45, the object of which is to open andclose the fuel channel 46 (drawn in dotted lines). This channel isclosed when the cam lug 4| lifts the rod 42. The effect of thisarrangement is that the motor does not receive with certainty any fuelthrough the main nozzle 34 when the throttle valve 35 is closed,irrespective of speed at which the car is running at the point of timeat which the ball valve 45 is closed. This second auxiliary device canbe applied, of course, as an attachment also to any other of the severalconstructional forms of carburetors described on the preceding pages.

In the practical employment of these improved carburetors also suchother known additional devices or appliances as, for instance, no-loadnozzles, acceleration pumps, starting devices, and the like, may becombined with any of said carburetors without impairing the greatereifect obtained by them. Additional devices of the mentioned varietieshave been omitted from the drawing as they do not form parts of theinvention and would, if likewise shown, only diminish the distinctnessof the disclosure.

I claim:

1. In a carburetor, a suction passage terminating at one end in an airintake opening, a throttle we located in said passage, a first venturilocated in said passage between said intake opening and said valve, asecond venturi located in said passage on the opposite side of saidvalve from said intake opening, a fuel nozzle located at said secondventuri, a fuel passage for delivering fuel from a float chamber to saidfuel nozzle, said nozzle having its discharge opening above the fuellevel in said float chamber, an air passage opening at one end into thesuction passage at said first venturi and opening at the other end intosaid fuel passage above the fuel nozzle opening, and means including anair valve mechanically linked with said throttle valve for controllingthe amount of air delivered by said air passage to said fuel passage.

2. A carburetor as claimed in claim 1, wherein the said air valve isarranged in the air passage to directly control the flow of air throughthe air passage.

3. A carburetor as claimed in claim 1, wherein the said air passage isprovided with an opening to the atmosphere and the air valve is arrangedto control the size of said opening.

4. A carburetor as claimed in claim 1, characterized by the provision ofa fuel valve in the fuel passage, and means for automatically closingsaid fuel valve when the throttle valve is completely closed.

LUDWIG BECK.

